Reduction of sti corner defects during spe in semicondcutor device fabrication using dsb substrate and hot technology

ABSTRACT

A device and method of reducing residual STI corner defects in a hybrid orientation transistor comprising, forming a direct silicon bonded substrate wherein a second silicon layer with a second crystal orientation is bonded to a handle substrate with a first crystal orientation, forming a pad oxide layer on the second silicon layer, forming a nitride layer on the pad oxide layer, forming an isolation trench within the direct silicon bonded substrate through the second silicon layer and into the handle substrate, patterning a PMOS region of the direct silicon bonded substrate utilizing photoresist including a portion of the isolation trench, implanting and amorphizing an NMOS region of the direct silicon bonded substrate, removing the photoresist, performing solid phase epitaxy, performing a recrystallization anneal, forming an STI liner, completing front end processing, and performing back end processing.

This is a continuation of U.S. application Ser. No. 11/847,053 filedAug. 29, 2007, the entirety of which is incorporated herein byreference.

FIELD OF INVENTION

The invention relates generally to semiconductor devices and moreparticularly to methods for reducing corner defects generated during SPEin shallow trench isolation in the manufacture of semiconductor devices.

BACKGROUND

Complementary metal oxide semiconductor (CMOS) devices (e.g., NMOS orPMOS transistors) have conventionally been fabricated on semiconductorworkpieces with a single crystal orientation (e.g., silicon having aMiller index (100)). Transistors within the CMOS devices, for example,are used in cell phones, laptop computers, etc., requiring greaterspeed, lower power consumption, higher reliability, and the like. Thespeed of the devices can be improved by increasing electron mobility,hole mobility, or both, using hybrid orientation technology (HOT).Electron mobility/movement for NMOS devices, for example, is high (e.g.,2-4 times higher) when the NMOS devices are built on a Miller index(100) substrate, however the hole mobility for PMOS devices is enhancedwhen the PMOS devices are fabricated on a Miller index (110) substrate.As a result, PMOS devices formed on a Miller index (110) surface willexhibit significantly higher drive currents than PMOS devices formed ona Miller index (100) surface. In other words, there is a desire toexploit the substrate orientation with Miller index (110) for pFETs andMiller index (100) for nFETs, for example. Previous endeavors to takeadvantage of this difference between NMOS and PMOS devices has resultedin hybrid substrates with different surface orientations using workpiececomposites to optimize the crystalline orientation of the NMOS and PMOSdevices, for example.

Direct silicon bonded (DSB) substrates are fabricated bychemo-mechanically bonding a film of single-crystal silicon of a firstcrystal orientation onto a base substrate having a different or secondcrystal orientation. Unlike, silicon-on-insulator (SOI) substrates, DSBsubstrates demonstrate “bulk-like” properties.

The industry continues to seek new approaches to “force” electriccharges to move at faster rates through the semiconductor devicechannels in an endless pursuit of increased circuit speeds and powerconsumption reductions. The ever decreasing size and scale ofsemiconductor device technology has presented numerous challenges. Forexample, gate leakage current due to sharp corner effects in thinsilicon gate oxide is a more pronounced problem with smaller devices.These sharp features can also increase stresses, produce large electricfields, create dislocations in the silicon, and ultimately fail thedevice, for example.

Crystallographic planes are significant in both the semiconductorcharacteristics and applications since different crystallographic planescan exhibit significantly diverse physical properties. For example,surface density of atoms (i.e., atoms/cm²) on various crystallographicplanes can differ substantially from each other. One of the standardnotations for the various planes is the Miller indices that are used todenote the crystallographic planes and the directions normal to thoseplanes. The general crystal lattice is represented by a set of unitvectors (e.g., a, b, and c) such that an entire crystal can bereplicated by copying the unit cell of the crystal and duplicating it ata given integer offset along the unit vectors. For example, reproducingthe basic cell at positions (n_(a))a+(n_(b))b+(n_(c))c, wherein n_(a),n_(b), and n_(c) are integers. It is not a requirement that the unitvectors be orthogonal.

FIGS. 1-3 show cubic crystals, with basic vectors in the x, y, and zdirections. Superimposed on the three crystal lattices are threedifferent planes indicated by the gray surface “partial planes”. Theplanes are shown in relation to the crystal axes x, y, and z by a set ofthree integers (e.g., (i₁i₂i₃)) where i₁ corresponds to the crystalplane's intercept with the x-axis, i₂ corresponds to the plane'sintercept with the y-axis and i₃ corresponds to the plane's interceptwith the z-axis. Given that parallel planes are equivalent planes, theintercept integers are reduced to the set of the three smallest integershaving the same ratios as the above intercepts. The Miller index (100),(010) and (001) planes correspond to the faces of a cube. The (111)plane intercepts the x, y, and z axis at 1, 1, and 1 respectively, andthe plane is tilted with respect to the cube faces. In representing anegative axis intercept, the corresponding Miller index is given as aninteger and a bar over the integer, similar to the (100) plane butintersecting the x axis at −1 instead of 1, for example.

Amorphization templated recrystallization (ATR) is an approach forproviding planar hybrid orientation substrates. Silicon is easilyamorphized by ion implantation and easily recrystallized by a subsequentannealing. FIGS. 4-10 outline examples of ATR methods for producinghybrid orientation silicon substrates. FIGS. 4-6 describe an ATR methodfor forming a bulk semiconductor hybrid orientation technology (HOT)substrate. FIG. 4 shows a starting substrate 400 comprising a lowersingle crystal semiconductor substrate 402 having a first crystalorientation (100) (Miller Index plane) in direct contact with an uppersecond single crystal semiconductor layer 404 having a second crystalorientation (110) different from the first orientation. The interface406, which is located between the semiconductor layers 402 and 404, istypically formed by a workpiece bonding process (e.g., direct siliconbonded (DSB) substrate) that is normally hydrophilic. The structure inFIG. 4 is often referred to as a mixed orientation DSB wafer or DSBworkpiece. The fabrication of the mixed orientation DSB workpiece iswell known by those of ordinary skill in the art.

FIG. 5 illustrates a structure 500 which results after the mixedorientation direct silicon bonded structure of FIG. 4 is subjected toion implantation 502 in selected areas to create localized amorphizationregions 504 extending from the top surface of semiconductor layer 404 toa depth ending in the substrate layer 402 below the interface 406.During anneal, the amorphized silicon will recrystallize to match theorientation of the crystalline silicon with which it is in contact. Itshould be noted that this process can be implemented, for example, withthe Miller Index (MI) (100) layer on top and the MI (110) layer on thebottom as opposed to the illustrated approach.

Subsequently, FIG. 6 shows a structure 600 which results from thestructure of FIG. 5 after localized amorphization regions 504 (FIG. 5)have been recrystallized, with the semiconductor layer 402 as atemplate, to form a single crystal semiconductor region 602 with theorientation of first semiconductor 402 (FIG. 5). The resulting substratenow comprises two clearly defined single-crystal semiconductor regionswith different surface orientations, e.g., non-amorphization regions 404of the second semiconductor layer and amorphization/recrystallizedregions 602. However, it should be noted that end-of-range defects 408remain in the structure at an approximate depth based upon theimplantation energy. These defects 408 are well known by those ofordinary skill in the art.

FIGS. 7-10 illustrate yet another example of a conventional ATR methodfor producing a semimconductor-on-insulator (SOI) hybrid orientationsubstrate. FIG. 7 shows a starting substrate structure 700 comprising ahandle substrate 702, an insulator layer 704, and a first single crystalsemiconductor layer 706 having a first crystal orientation in directcontact with a second single crystal semiconductor layer 708 having asecond crystal orientation different from the first. The interface 710between semiconductor layers 706 and 708 is typically formed by aworkpiece bonding process.

FIG. 8 shows a structure 800 which results when the structure of FIG. 7is subjected to ion bombardment 802 in selected areas to createlocalized amorphization regions 804 extending from the top surface ofinsulator layer 704 up to and ending in semiconductor layer 708 aboveinterface 710. FIG. 9 shows a structure 900 which results from thestructure of FIG. 8 after localized amorphization regions 804 have beenrecrystallized, using semiconductor layer 708 as a template to formsingle crystal semiconductor region 902 (FIG. 9) with the orientation ofupper semiconductor 708. Upper semiconductor layer 708 is then removedby a process (for example, polishing, oxidation/wet etching, or thelike) to produce substrate 1000 of FIG. 10. Substrate 1000 comprises twoclearly defined single-crystal semiconductor regions with differentsurface orientations, e.g., non-amorphization regions 706 of the secondsemiconductor layer and amorphization recrystallization region 1004, onthe insulator layer 704. Regions 706 and 1004 may be further thinned(again by processes such as polishing and/or oxidation/wet etching), ifthinner semiconductor-on-insulator structures are desired.

FIGS. 11-13 represent a conventional approach to forming a CMOS hybridorientation device utilizing amorphization templated recrystallization(ATR) prior to shallow trench isolation (STI) formation. FIG. 11 shows astarting mixed orientation direct silicon bonded substrate 1100comprising a lower single crystal semiconductor substrate 1102 having afirst crystal orientation (100) in direct contact with an upper secondsingle crystal semiconductor layer 1104 having a second crystalorientation (110) (e.g., Miller Index) different from the firstorientation. The interface 1106, which is located between thesemiconductor layers 1102 and 1104, is typically formed by a workpiecebonding process. The workpiece bonding process is well known by one ofordinary skill in the art.

FIG. 12 illustrates a photoresist layer 1202 patterned on the PMOSregion of device 1200, as shown in FIG. 11. The device 1200 is thensubjected to ion implantation 1204 in the selected areas to createlocalized amorphization regions 1206 extending from below the lowersurface of semiconductor layer 1104 within the first silicon layer 1102to the top of the substrate layer 1104. The ion implantation 1204 can,for example, comprise silicon, germanium, and the like.

Subsequently, FIG. 13 shows the structure of FIG. 12 after localizedamorphization regions 1206 have been recrystallized, with thesemiconductor layer 1102 acting as a template, to form a single crystalsemiconductor region 1302 with the orientation of first semiconductor1102. The resulting substrate 1300 now comprises two clearly definedsingle-crystal semiconductor regions with different surfaceorientations, e.g., non-amorphization region 1104 of the secondsemiconductor layer and amorphization/recrystallized region 1302. Inother words, the PMOS region maintains the original orientation (110)DSB layer 1104 and (100) bulk workpiece control. The ATR layer 1206(FIG. 12) of the NMOS has been changed, for example, from firstcrystalline orientation (110) to second crystalline orientation (100).An STI 1306 can then formed, as shown. The formation of the STI 1306 iswell known by those of ordinary skill in the art. The amorphized layer1206 (FIG. 12) can be redone utilizing a solid phase epitaxy (SPE)process 1304 to align the buffer layer 1302 to the (100) surface 1102,so that the buffer layer 1302 becomes a (100) surface, as illustrated.

FIG. 14A is provided to show a transmission electron microscopy (TEM)image of border region defects, with the cut perpendicular to theworkpiece notch prior to the formation of the STI. FIG. 14A illustratesa defect 1402 that occurs in the prior art method illustrated in FIGS.11-13, for example during the “recrystallization process.” As theamorphized layer 1206 is redone utilizing the SPE process 1304, thelayer 1408 wants to grow vertically as it is transformed from anamorphized (110) crystal to a (100) crystal during SPE. The (110) layer1406 that has not been amorphized wants to grow laterally during SPE,thereby forming a defect 1402 shown in device 1400. As shown in FIGS.14A and 14B, the workpiece 1410 is cut or cross-sectioned perpendicularto the workpiece notch 1412. As discussed, there is competition betweenthe horizontal/lateral templating (110) and the vertical templating(100) as shown, wherein the crystallographic planes ((100) and (110))cause the residual corner defects 1402, as illustrated in FIG. 14A.Subsequent STI trenches and STI can be formed that replace the angularmorphology 1404 containing the defects 1402. However, the angularmorphology 1404 has a given width and the STI width can be very small,and it may not be possible to replace all of the defects in the angularmorphology 1404 with a given STI. FIG. 14B illustrates the workpiece1410, workpiece notch 1412 and notch orientation 1414, wherein theworkpiece 1410 is cut in cross-section with orientation 1416, as shown,perpendicular to the notch orientation 1414.

As illustrated for the device 1500 in FIGS. 15A and 15B, the workpiece1510 is cut or cross-sectioned parallel to the workpiece notch 1512.There is competition between the horizontal/lateral templating (110) inarea 1506 and the vertical templating (100) of area 1508 as shown,wherein the crystallographic planes ((100) 1508 and (110) 1506) causethe residual corner defects 1502, as illustrated in FIG. 15A. Asmentioned above, subsequent STI can be formed to replace the angularmorphology 1504 containing the defects 1502 shown in FIG. 15A. Asdiscussed, the angular morphology has a given width for a given processand the STI width is or can be very small and it may not be possible toreplace all of the defects 1502 in the angular morphology 1504 with agiven STI width. FIG. 15B illustrates the workpiece 1510, workpiecenotch 1512 and notch orientation 1514 wherein the workpiece 1510 is cutin cross-section orientation 1516, as shown, parallel to the notchorientation 1514. These illustrations clearly show theissues/problems/defects that are present with the conventioinal approachto performing ATR prior to STI formation. These defects can and havebeen corrected with extremely high temperature anneals (e.g., greaterthan 1250 degrees Celsius); however those temperatures can cause otherdefects, such as large stresses that can warp the workpiece, and thelike.

FIGS. 16-18 represent a second conventional approach to forming a CMOShybrid orientation device utilizing amorphization templatedrecrystallization (ATR) after STI formation. FIG. 16 shows a startingdevice 1600 comprising a lower single crystal semiconductor substrate1602 having a first crystal orientation (100) in direct contact with anupper second single crystal semiconductor layer 1604 having a secondcrystal orientation (110) (e.g., Miller Index) different from the firstorientation. As discussed above, the interface 1606, which is locatedbetween the semiconductor layers 1602 and 1604, is typically formed by aworkpiece bonding process, e.g., DSB. Workpiece bonding processes arewell known by those of ordinary skill in the art and all arecontemplated herein.

FIG. 17 illustrates a device 1700 with an STI 1702 formed into andthrough the (110) Miller index layer 1604 and into a portion of the(100) handle substrate 1602, for example. The formation of the STI 1702is well known by those of ordinary skill in the art. A photoresist layer1704 is subsequently patterned on the PMOS region of the device 1700, asshown in FIG. 17. The device 1700 is then subjected to ion implantation1706 in the selected areas to create localized amorphization regions1708 extending from below the lower surface of semiconductor layer 1604within the first silicon layer (100) 1602 to the top of the substratelayer 1604. The ion implantation 1706 can, for example, comprisesilicon, germanium, and the like.

FIG. 18 shows the device of FIG. 17 after localized amorphizationregions 1708 (FIG. 17) have been recrystallized, with the semiconductorlayer 1602 acting as a template, to form a single crystal semiconductorregions (100) 1602 and 1806, both with the orientation of firstsemiconductor (100). The resulting device 1800 now comprises two clearlydefined single-crystal semiconductor regions with different surfaceorientations, e.g., non-amorphization regions (110) 1604 of the secondsemiconductor layer and amorphization/recrystallized regions 1806. Theamorphized layer 1708 (FIG. 17) can be redone utilizing a solid phaseepitaxy (SPE) process 1804 to align the buffer layer 1708 (FIG. 17) tothe (100) surface/layer 1602, so that the buffer layer 1708 becomes a(100) surface/layer, as illustrated. Advantages of this approach includeno lateral templating; however there are trench edge and corner defectscreated using this technology from vertical templating and the like. Thedefects are created when the uniform recrystallization stops on the(111) plane (FIG. 3) because the (111) plane meets the surface of theSTI at, for example, 54 degrees.

FIG. 19 shows an example transmission electron microscopy (TEM) image ofborder region defects of a device 1900, with the TEM cut parallel to theworkpiece notch. FIG. 19 illustrates common defects 1902 that occur inangular morphology 1904 with the conventional method illustrated inFIGS. 16-18. As the amorphized layer 1708 (FIG. 17) is redone utilizingthe SPE process 1804 (FIG. 18), the surface of the STI 1702 restrainsthe crystals from regrowing in an unrestrained manner.

Accordingly, there is a need for improved semiconductor processes anddevices to overcome the problems in the art, such as outlined above.

SUMMARY

In one aspect, the invention provides a device with reduced residual STIcorner defects formed by the process of forming a direct silicon bondedsubstrate wherein a second silicon layer with a second crystalorientation is bonded to a handle substrate with a first crystalorientation, forming a pad oxide layer on the second silicon layer,forming a nitride layer on the pad oxide layer, forming an isolationtrench within the direct silicon bonded substrate through the secondsilicon layer and into the handle substrate, patterning a PMOS region ofthe direct silicon bonded substrate utilizing photoresist including aportion of the isolation trench, implanting and amorphizing an NMOSregion of the direct silicon bonded substrate, removing the photoresist,performing solid phase epitaxy, performing a recrystallization anneal,completing front end processing, and performing back end processing.

In another aspect, the invention provides a method of fabricating asemiconductor device with reduced residual STI corner defects comprisingforming a direct silicon bonded substrate wherein a second silicon layerwith a second crystal orientation is bonded to a handle substrate with afirst crystal orientation forming a pad oxide layer on the secondsilicon layer, forming a nitride layer on the pad oxide layer, formingan isolation trench within the direct silicon bonded substrate throughthe second silicon layer and into the handle substrate, patterning aPMOS region of the direct silicon bonded substrate utilizing photoresistincluding a portion of the isolation trench, implanting and amorphizingan NMOS region of the direct silicon bonded substrate, removing thephotoresist, performing solid phase epitaxy, performing arecrystallization anneal, forming an STI liner, completing front endprocessing and performing back end processing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 are perspective views illustrating Miller Index (010), MillerIndex (110) and Miller Index (111) according to an aspect of theinvention;

FIGS. 4-6 (Prior Art) are cross-sectional views illustratingconventional ATR structures at various stages in the manufacturingprocess;

FIGS. 7-10 (Prior Art) are cross-sectional views illustrating aconventional ATR device fabrication;

FIGS. 11-13 (Prior Art) are cross-sectional views illustrating aconventional method for forming a device utilizing ATR prior to STIformation;

FIGS. 14A, 14B, 15A and 15B (Prior Art) illustrate defects that occurutilizing the conventional method of FIGS. 11-13;

FIGS. 16-18 (Prior Art) are cross-sectional views illustrating aconventional method for forming a device utilizing ATR after STIformation;

FIG. 19 (Prior Art) illustrates defects that occur utilizing theconventional method of FIGS. 16-18;

FIGS. 20-24 and 25A are cross-sectional views of the formation ofdevices utilizing ATR prior to STI formation according to aspects of theinvention;

FIG. 25B is an illustration based on a photograph, showing theelimination of defects in a device, according to yet another aspect ofthe invention;

FIG. 26 is a flowchart demonstrating ATR prior to STI formation,according to aspects of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

An example implementation of the principles of the invention isdescribed in the context of embodiment of a semiconductor deviceincluding an STI (shallow trench isolation) region. In the fabricationof semiconductor devices, isolation structures are formed between activeareas in which electrical devices such as transistors, memory cells, orthe like, are to be formed. The isolation structures, in this case STIstructures, are typically formed during initial processing of asemiconductor substrate, prior to the formation of such electricaldevices.

A modified amorphization templated recrystallization (ATR) approach forproviding planar hybrid orientation substrates can be utilized in theinvention. As discussed supra, silicon is easily amorphized by ionimplantation and easily recrystallized by subsequent SPE processing andannealing. The inventive solution enables the elimination of STI cornerdefects without the use of a subsequent anneal at extremely hightemperature (e.g., greater than 1250 degrees Celsius) that can generateundesired mechanical stresses resulting in workpiece warping, and thelike.

FIGS. 20-24 and 25A illustrate an ATR method for producing reduceddefect hybrid orientation silicon substrates. This is accomplished byutilizing ATR prior to STI formation. FIG. 20 shows a starting device2000 comprising a lower single crystal semiconductor substrate 2002(“handle substrate”) having a first crystal orientation (100) in directcontact with an upper single crystal semiconductor layer 2004 having asecond crystal orientation (110) (e.g., Miller Index) different from thefirst orientation. The upper single crystal semiconductor layer 2004 canhave a thickness of approximately 100-300 nm, for example. The interface2006, which is located between the semiconductor layers 2002 and 2004,is typically formed by a workpiece bonding process (e.g., direct siliconbonded (DSB)) that can be hydrophobic, hydrophilic, and the like, forexample. The structure in FIG. 20 is often referred to as a mixedorientation DSB wafer or DSB workpiece. It should be noted that inanother embodiment of the invention the lower substrate can have acrystal orientation of (110) and the upper layer a crystalline structure(100) and both orientations, and the like are contemplated herein.

Device 2100 in FIG. 21 is the device 2000 of FIG. 20 wherein a siliconoxide 2102 (e.g., 10-20 nm) can be formed on the silicon (110) layer2004. The dielectric 2102 is formed on the substrate 2004 outer surfaceand is often referred to as a “pad-oxide”. The pad oxide 2102 acts, forexample, as an intermediate layer or barrier between the siliconsubstrate upper layer 2004 and a silicon nitride layer 2104 that isdeposited on top of the pad oxide 2102 in subsequent processing. Thenitride layer 2104 (e.g., 150-200 nm) can be deposited using severaltechniques which include deposition by evaporation, sputtering,chemical-vapor deposition (CVD), and the like. These depositiontechniques are well known by those of ordinary skill in the art. Thelayers, 2102 and 2104, can protect the surface of “active areas” fromsubsequent chemical mechanical polishing (CMP), for example.

The nitride layer 2104 can provide protection for an electrical deviceactive area formation during shallow trench creation. The nitride layer2104 can be, for example, SiN, silicon nitride (Si₃N₄), reaction bondedsilicon nitride (RBSN), hot pressed silicon nitride (HPSN), sinteredsilicon nitrides (SSN), and the like. The dielectric layer 2102 and thenitride layer 2104 together form what is referred to as a “hard mask”.During pattern transfer to an integrated circuit device, the hard masklayer is consumed during an etching process, for example. However, it isto be appreciated that any hard mask techniques may be practiced in thisinvention, and that other hard mask materials and masking processes arecontemplated as falling within the scope of the invention.

A conventional photoresist (not shown) can be applied, for example andcan be utilized to pattern and etch the nitride layer 2104 and the padoxide layer 2102 in order to result in a patterned and etched device2200 with a resultant STI trench 2206. The photoresist can be, forexample, a solvent-based, light-sensitive resin solution that isuniformly applied, for example, on the nitride layer 2104 of the device2200, utilizing a spin type process, and the like. The photoresist can,for example, be a chemical, negative photoresist that hardens whenexposed to ultraviolet light or other light wavelengths and theunexposed photoresist can be dissolved by employing a developer solvent,leaving openings in the exposed photoresist. Another approach involvesutilizing a positive photoresist that is initially insoluble, and whenexposed to e.g., UV, mercury light, laser, x-rays, electron beam, etc.,becomes soluble. After exposure, the photoresist can create the etchpattern needed to form the active STI trenches 2206 during, for example,reactive ion etching (RIE).

Referring to FIG. 23, a photoresist 2302 can be formed over the PMOSactive area as illustrated. The photoresist 2302 can be applied to thedevice 2300 followed by patterning involving photoresist removal and astandard clean in FIG. 23 that is well known by those of ordinary skillin the art. The device can be implanted 2304 utilizing Si⁺ and/or Ge⁺through the nitride-oxide hard mask, for example. The implant dose andenergy can be in the range of 2.5-5.0E15/cm² and 200-300 keV,respectively, for example. FIG. 23 shows the device 2300 after the firstsilicon layer has been amorphized (α-Si) by ion implantation 2304 tocreate amorphous layer 2306 extending past the location of the originalbonded interface 2006. Lateral re-growth 2306 takes place under a smallportion of the area covered by the photoresist. The amorphized (“α-Si”)layer 2308 can be approximately 250-350 nm deep, for example.

In FIG. 24, the change of the crystal orientation of the top siliconlayer 2402 can be realized as an amorphized top layer which will re-growaligned to the handle workpiece 2002 crystalline structure. SPE can berealized by low temperature anneal in an Ar, N₂ or H₂ environment, forexample. Typical ranges for temperatures can be respectively 400-700degrees Celsius. After SPE, an annealing process (e.g., less than 1250degrees Celsius, 10 sec, N₂, Ar or H₂ environment) can be performed toreduce residual crystal damage. The damage can be in the form of stableend-of-range damage induced dislocation loops located at theamorphous/silicon interface, STI corner defects, and the like, forexample. In order to be able to remove the corner defects withoutapplying extremely high conventional temperature anneals (e.g., greaterthan 1250 degrees Celsius) the SPE will be conducted before the oxide2504 filling and oxide lining 2502 of the trench. The “free” sidewallsurface 2404 (FIG. 24) provides the silicon atoms more freedom inrealigning to the handle workpiece crystalline structure during SPE. Inother words, the atoms are not constrained at the sidewall surface.

FIG. 24 shows a structure 2400 after a solid phase epitaxy (SPE) 2406.The ion implantation 2304 ((FIG. 23) occurs prior to the annealingprocess. If the ion implantation energy of the impurity atoms issufficiently high, it can damage the silicon of the surface of thesilicon substrate. A damage reducing anneal is sufficient to producere-growth of the amorphized silicon by solid-phase epitaxy 2402 torestore the surface of the silicon substrate with minimal crystaldefects, for example. The SPE process 2406 is well known by those ofordinary skill in the art and can be performed prior to STI sidewallformation. It should be noted that the invention eliminates many of theresidual STI corner defects generated in other approaches.

The device 2400 in FIG. 24 continues at FIG. 25A, for example, with thedeposition or forming of a dielectric trench liner 2502 that can beformed over the exposed portions of the STI trench 2206. The trenchdielectric liner 2502 can be deposited or formed in any suitableprocess, such as, a thermal growth process at the exposed trenchsurfaces of the etched STI trench. As discussed supra, the trenchdielectric liner 2502 can be deposited to act as a protective layer forthe trench, to act as a high purity spacer between the silicon and afill dielectric 2504, and the like. The trench lining process can be,for example, a thermal process, a LVCVD process, a thermal processbi-layered liner, a chemical oxide process in combination with LPCVDfilms, and the like. It should be apparent to those of ordinary skill inthe art that other trench liner materials (e.g., nitride), multipleisolation liners, no liners at all, and the like are contemplated withthis invention.

In FIG. 25A, for example, the trench 2206 can then be filled with agap-filling oxide isolation material 2504. The structure is subsequentlychemically mechanically polished (CMP) to create a planar STI structure(e.g., approximately 300 nm deep, for example) such that electricaldevices (inner active areas) can be formed within regions bounded by theSTI, often referred to as moats. Subsequently, the nitride layer can beremoved. It should be appreciated that any process known by those ofordinary skill in the art to remove the nitride layer is contemplatedwithin this invention. The isolation nitride, for example, can beremoved with phosphoric acid at an elevated temperature and SC1megasonic processing. In addition, the pad oxide layer has been removedusing techniques known by those of ordinary skill in the art. It is tobe appreciated that at this point in the process the workpiece will beprocessed according to usual metal-oxide-semiconductor STI process flowsknown to those of ordinary skill in the art to complete the first option(ATR prior to STI formation).

FIG. 25B is provided by applicants of the invention to show atransmission electron microscopy (TEM) image of the reduction of borderregion defects utilizing ATR after the STI etching process. Comparingthe FIG. 25B (associated with the inventive process) to FIG. 19 (priorart approach), the new inventive approach is clearly superior to theprior art approach in terms of defect reduction and/or elimination.

Referring to FIG. 26, an example method 2600 is illustrated as a flowdiagram for fabricating a MOS device in accordance with one or moreaspects of the invention. It will be appreciated that the invention isnot limited by the illustrated ordering of such acts or events. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein, in accordance with the invention. In addition, not allillustrated steps may be required to implement a methodology inaccordance with the invention. Furthermore, the methods according to theinvention may be implemented in association with the formation and/orprocessing of structures illustrated and described herein as well as inassociation with other structures not illustrated. In one example, themethod 2600 or variants thereof, may be used in manufacturing CMOSdevices, as illustrated and described above with respect to FIGS. 20-24and 25A.

Beginning at 2602 of FIG. 26, a handle substrate with a firstorientation (100) is provided at 2604. A second substrate with a secondcrystalline orientation (110) is bonded to the handle substrate at 2606.The second crystal semiconductor layer can have a thickness ofapproximately 100-300 nm, for example. It will be appreciated that thebonding process can be performed utilizing a DSB substrate preparationprocess as is well known to those of ordinary skill in the art. In oneexample technique each surface being bonded to another surface can besubjected to a pre-bonding treatment. The pre-bonding treatment caninclude a cleaning process, an activation process, and the like, of thesurfaces to be bonded to together. The cleaning process can includeconventional standard clean processes; plasma activated cleaning, andthe like. Bonding can occurs via hermetic bonding techniques,non-hermetic bonding techniques, or combinations of these techniques,depending upon the specific approach and/or embodiment. The hermetictechniques include anodic, eutectic, fusion, covalent, and the like. Thenon-hermetic techniques include epoxy, glue films, liquid crystalpolymer (LCP), and others. One of ordinary skill in the art wouldrecognize many other variations, modifications, and alternatives tothose presented herein.

At 2608 a pad oxide layer (e.g., 10-20 nm) can be formed over the secondsubstrate (110) utilizing a thermal oxide process, for example. Anyappropriate process steps and materials can be employed in the formationof the oxide layer at 2608, including oxidation processes as are wellknown to those of ordinary skill in the art. At 2610 a nitride layer(e.g., 150-200 nm) can be formed over the oxide layer at 2608. Knowndeposition processes by those of ordinary skill in the art can beemployed in the formation of the nitride layer at 2610. The nitridelayer, as discussed in FIG. 21 above can be, for example, siliconnitride, reaction bonded silicon nitride, hot pressed silicon nitride,sintered silicon nitrides, and the like. At 2612 active areas arecreated in composite substrate and active areas of substrate are coatedwith a photoresist and subsequently exposed to light through openings ina photoresist mask, for example. The active areas can be created usingtechniques that are well known to those of ordinary skill in the art. Asdescribed in FIG. 22, supra, the photoresist can be, for example, asolvent-based, light sensitive resin solution that softens or becomessoluble when exposed to light (positive photoresist). Any appropriateprocess steps, materials or energy may be utilized in forming thephotolytic mask and exposing the photoresist.

The methodology continues at 2614, where a soluble photoresist (exposedor un-exposed), for example is developed or etched away exposing theouter surface of the nitride layer formed at 2610. The process at 2614results in a pattern being formed on the substrate allowing for STItrench formation. At 2616 a nitride layer and oxide layer etchingprocess can be performed. As disclosed in FIG. 22. Any suitablefabrication steps or materials can be employed in etching the oxide andnitride layers as are known, for example, wet etching techniques, or dryetching techniques, or both.

At 2616 a recessed active trench can be created in the substrate. Theetching procedure may be, for example, a single step or multi-stepprocess, a wet or dry etch process, by which material is removed in theexposed isolation regions in the semiconductor substrate to form theisolation trenches. At 2618 the photoresist is removed. The process ofremoving photoresist is well known by those of ordinary skill in theart. The oxide and nitride layers can protect the surface of “activeareas” from subsequent chemical mechanical polishing (CMP), for example.The nitride layer can provide protection for an electrical device activearea formation during shallow trench creation. The nitride layer can be,for example, SiN, silicon nitride (Si₃N₄), reaction bonded siliconnitride (RBSN), hot pressed silicon nitride (HPSN), sintered siliconnitrides (SSN), and the like. The example method 2600 continues at 2620,for example, a photoresist can be formed over the PMOS active area asillustrated. The photoresist can be applied to the device followed bypatterning involving photoresist removal and a standard clean in that iswell known by those of ordinary skill in the art. The device can beimplanted utilizing Si⁺ and/or Ge⁺ at 2622 through the nitride-oxidehard mask, for example as discussed supra. The implant dose and energycan be in the range of 2.5-5.0E15/cm² and 200-300 keV, respectively, forexample. The device after the first silicon layer has been amorphized(α-Si) by ion implantation to create an amorphous layer. The amorphizedlayer can be approximately 250-350 nm deep, for example.

The change of the crystal orientation of the top silicon layer can berealized as an amorphized top layer which will re-grow aligned to thehandle workpiece crystalline structure, for example. SPE can be employedat 2624 by a low temperature anneal in an Ar, N₂ or H₂ environment, forexample. Typical ranges for temperatures can be respectively 400-700degrees Celsius. After SPE, an anneal (e.g., greater than 1050 but lessthan 1250 degrees Celsius, 10 sec, N₂, Ar or H₂ environment) can beapplied to reduce residual crystal damage. The damage can be in the formof stable end-of-range damage induced dislocation loops located at theamorphous/silicon interface, STI corner defects, and the like, forexample. The inventors recognized that by keeping the anneal temperaturebelow 1250 degrees Celsius that wafer warpage defects, and the likewould be reduced. In order to be able to remove the corner defectswithout applying extremely high conventional temperature anneals (e.g.,greater than 1250 degrees Celsius) the SPE can be conducted before theoxide lining and oxide filling of the trench. The “free” sidewallsurface of the trench provides the silicon atoms more freedom inrealigning to the handle workpiece crystalline structure during SPE. Theatoms are not constrained and there for can move at the sidewallsurface.

This can be followed at 2626 with the deposition or forming of adielectric trench liner that can be formed over the exposed portions ofthe STI trench. The trench dielectric liner can be deposited or formedin any suitable process step, such as, a thermal growth process at theexposed trench surfaces, including sidewall recesses and center sectionof the etched STI trench. As discussed supra, the trench dielectricliner can be deposited to act as a protective layer of the trench, toact as a high purity spacer between the silicon and the fill dielectric,and the like. The trench lining process can be, for example, a thermalprocess, a LVCVD process, a thermal process bi-layered liner, a chemicaloxide process in combination with LPCVD films, and the like. It shouldbe apparent to those of ordinary skill in the art that other trenchliner materials (e.g., nitride), multiple isolation liners, no liners atall, and the like are contemplated with this invention. At 2626 thefront end processing can be completed, for example. Front end processingcan include filling the STI trench with oxide and chemical mechanicalpolishing, and the like.

The example method 2600 continues at 2628, for example, where back endprocessing can be completed. The back end processing of CMOS devices iswell known by those of ordinary skill in the art and can include formingmetal interconnect layers, and the like. The process ends at 2630.

Those skilled in the art to which the invention relates will appreciatethat other embodiments and modifications are possible within the scopeof the claimed invention.

1-7. (canceled)
 8. A method of fabricating a semiconductor device,comprising: forming a direct silicon bonded substrate wherein a secondsilicon layer with one of a (100) or (110) crystal orientation is bondedto a first silicon layer of a handle substrate with the other of the(100) or (110) crystal orientation; forming a pad oxide layer over thesecond silicon layer; forming a nitride layer over the pad oxide layer;forming an isolation trench within the direct silicon bonded substratethrough the second silicon layer and into the first silicon layer; afterforming the isolation trench, performing a patterned implant toamorphize a region of the second silicon layer; performing solid phaseepitaxy at a temperature of less than about 700° C. to recrystallize theamorphized region of the second silicon layer to the same crystalorientation as the first silicon layer; and after performing the solidphase epitaxy, filling the isolation trench with an isolation material.9. The method of claim 8, further comprising, after performing the solidphase epitaxy, performing an anneal at a temperature of greater thanabout 1050° C. but less than 1250° C. to repair residual crystal damage.10. The method of claim 9, wherein filling the isolation trench with anisolation material comprises growing an oxide liner on sidewalls of theisolation trench, forming a layer of oxide including over the oxideliner to fill the trench, and mechanically planarizing the layer ofoxide to remove portions outside the isolation trench.
 11. The method ofclaim 10, wherein the solid phase epitaxy is performed at a temperatureof 550-650° C. for a time of 0.6-35 minutes.
 12. The method of claim 10,wherein the patterned implant is performed by implanting at least one ofsilicon or germanium into the second silicon layer.
 13. The method ofclaim 12, wherein the implant is performed using a dosage of 2.5-5.0E15atoms/cm² at an energy of 200-300 keV.
 14. The method of claim 12,wherein one of an NMOS or PMOS transistor is formed in the amorphizedregion of the second silicon layer after recrystallization, and theother of the NMOS or PMOS transistor is formed in an unamorphized regionof the second silicon layer, with the oxide filled trench serving toisolate the NMOS transistor from the PMOS transistor.
 15. The method ofclaim 8, wherein filling the isolation trench with an isolation materialcomprises growing an oxide liner on sidewalls of the isolation trench,forming a layer of oxide including over the oxide liner within thetrench, and mechanically planarizing the layer of oxide to removeportions outside the isolation trench.
 16. The method of claim 8,wherein filling the isolation trench with an isolation materialcomprises growing an oxide liner on sidewalls of the isolation trench,forming a layer of oxide including over the oxide liner to fill thetrench, and mechanically planarizing the layer of oxide to removeportions outside the isolation trench.
 17. The method of claim 16,wherein one of an NMOS or PMOS transistor is formed in the amorphizedregion of the second silicon layer after recrystallization, and theother of the NMOS or PMOS transistor is formed in an unamorphized regionof the second silicon layer, with the oxide filled trench serving toisolate the NMOS transistor from the PMOS transistor.
 18. The method ofclaim 8, wherein the solid phase epitaxy is performed at a temperatureof 550-650° C. for a time of 0.6-35 minutes.
 19. A method of fabricatinga semiconductor device, comprising: forming a direct silicon bondedsubstrate wherein a second silicon layer with a (110) crystalorientation is bonded to a first silicon layer of a handle substratewith the (100) crystal orientation; forming a hardmask over the secondsilicon layer, the hardmask comprising a silicon oxide layer and asilicon nitride layer; patterning the hardmask with an opening, andetching the second silicon layer and at least a portion of the firstsilicon layer through the opening to form an isolation trench toseparate PMOS and NMOS active areas within the direct silicon bondedsubstrate; after forming the isolation trench, performing a patternedimplant to amorphize the second silicon layer selectively in the NMOSactive area; performing solid phase epitaxy at a temperature of lessthan about 700° C. to recrystallize the amorphized region of the secondsilicon layer to the same crystal orientation as the first siliconlayer; and after performing the solid phase epitaxy, filling theisolation trench with an isolation material by growing an oxide liner onsidewalls of the isolation trench, forming a layer of oxide includingover the oxide liner within the trench, and mechanically planarizing thelayer of oxide to remove portions outside the isolation trench.
 20. Themethod of claim 19, wherein the patterned implant comprises implantingat least one of silicon or germanium through the hardmask.
 21. Themethod of claim 20, wherein the implant of at least one of silicon orgermanium is performed using a dosage of 2.5-5.0E15 atoms/cm² at anenergy of 200-300 keV.
 22. The method of claim 21, further comprising,after performing the solid phase epitaxy, performing an anneal at atemperature of greater than about 1050° C. but less than 1250° C. torepair residual crystal damage.
 23. The method of claim 22, wherein thesolid phase epitaxy is performed at a temperature of 550-650° C. for atime of 0.6-35 minutes.
 24. The method of claim 19, wherein the solidphase epitaxy is performed at a temperature of 550-650° C. for a time of0.6-35 minutes; and further comprising, after performing the solid phaseepitaxy, performing an anneal at a temperature of greater than about1050° C. but less than 1250° C. to repair residual crystal damage. 25.The method of claim 19, wherein the second silicon layer is bonded tothe first silicon layer at an interface; and the patterned implant alsoamorphizes a portion of the first silicon layer to create an amorphouslayer extending below the location of the interface.
 26. The method ofclaim 25, wherein the amorphized portion of the first silicon layercomprises a portion located below the isolation trench.
 27. The methodof claim 26, wherein the second silicon layer has a thickness ofapproximately 100-300 nm and the amorphous layer is approximately250-350 nm deep.